At that age, I was already visiting the island. You can bet I'd want my own damn car and to do whatever I wanted...... <img src="http://www.traveltalkonline.com/forums/images/graemlins/Groovin.gif" alt="" />....give them some ideas but let everyone chill as they wish. Build in some time to make mutual memories, but don't micromanage.
There had been a trip report here last year by a guy that stayed in a villa near Orient with his adult sons. Perhaps one was married.(?) their trip sounded so nice. Family dinners, push-up contests, pool time, individual time, etc.